Double acting hydraulic cushioning device



Oct. 20, 1970 o. w. DAUGH'ERTY, JR

Filed March 5, 1969 6 Sheets-Sheet 1 5 43 60 71} j ia 78 \\x\\\\y&% g

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DOUBLE ACTING HYDRAULIC CUSHIONING DEVICE' Filed March 5, 1969 6 Sheets-Sheet 2 D. W. DAUGHERTY, JR

DOUBLE ACTING HYDRAULIC CUSHIONING DEVICE 6 Sheets-Sheet 5 Oct. 20, 1970 Filed March 3, 1969 Oct. 20, 1970 D. w. DAUGHERTY, JR 3,534,370

DOUBLE ACTING HYDRAULIC CUSHIONING DEVICE Filed March 5, 1969 6 Sheets-Sheet &

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DOUBLE ACTING HYDRAULIC CUSHIONING DEVICE Filed March 5, 1969 6 Sheets-Sheet 5 W//////////%/ 4% w? l v\ "2 6 Sheets-Sheet 6 n w 0 I W W W. J. W %W 2 n. w. DAUGHERTY, JR

DOUBLE ACTING HYDRAULIC CUSHIONING DEVICE Oct. 20., 1970 Filed March 5, 1969 United States Patent O US. Cl. 2138 13 Claims ABSTRACT OF THE DISCLOSURE A two-way hydraulic unit particularly adapted for use as a cushioning device when mounted on the end of a railroad car, in which a ram is mounted in a closed cylinder fixed to the underside of the car, a slidable element to which the car coupler is secured imposes both buff and draft forces on the ram mounted in the cylinder, and a shiftably mounted orifice controlling metering pin mounted in the ram controls the flow of hydraulic fluid from the high pressure side of the cylinder to a low pressure chamber during both buff and draft. An expansible storage chamber is provided into which fluid can flow through a double acting check valve from the low pressure side only of the cylinder. The unit may be provided with springs and spring retaining canisters and bolts at the four corners to return the unit to its neutral position, or a single coil spring may be used to return the unit and resilient cushioning means may be provided to give the cylinder limited movement during draft and cushion the draft impacts when the ram head is adjacent the rod end of the cylinder.

This application is a continuation-in-part of application Ser. No. 718,551 filed in the US. Patent Oflice Apr. 3, 1968.

BRIEF SUMMARY OF THE INVENTION Hydraulic units suitable for mounting on the end of railroad cars to absorb impacts are well known. Several of such units are shown and described in US. Pats. Nos. 3,150,782 and 3,368,698. These units are one-way shock absorbers designed to act as such only when the unit is being compressed, and do not absorb energy when the unit is being expanded, or returned to neutral position. The present invention is a two-way unit adapted to absorb shock both when the unit is being compressed and when being expanded. In order to enable the present invention to act as a two-way hydraulic unit, as compared to those of above mentioned patents the hydraulic cylinder is closed at the rear end instead of leaving it open so that fluid can flow directly therefrom into the expansible boot attached to the rear end of the cylinder, thereby creating two separate chambers within the cylinder, one on either side of the ram or piston. The piston or ram head is equipped with a two-way check valve so that fluid cannot flow from the high pressure side of the cylinder into the boot. The metering pin is constructed in such way that it will open due to high pressure fluid in either of the two cylinder chambers. A slidable element keyed to the coupler is adapted to 'exert both impact and draft or pull on the ram. A solid compressible cushioning element is provided to cushion the impact of the hydraulic unit against a stroke-limiting stop element during draft. Suitable spring guides and spring elements are provided to return the unit to starting or neutral position.

FIGS. 1 and 1A represent in two parts a vertical cross- 3,534,870 Patented Oct. 20, 1970 section of the ram and cylinder structure forming part of the invention;

FIGS. 2 and 2A represent in two parts a horizontal cross-section through the center of the hydraulic unit, illustrating the invention with certain parts shown in plan view;

FIGS. 3 and 3A represent in two parts a vertical longitudinal cross-section through the center of the hydraulic 'unit, illustrating the invention, with certain parts shown in elevational view;

FIG. 4 is a cross-sectional view, half of which is taken along the line 44 of FIG. 2 and the other half of which is taken along the line 44 of FIG. 2A;

FIG. 5 is a longitudinal cross-sectional View of a modified ram and metering structure useful in accordance with the invention;

FIG. 6 is an end view of a spring plate forming part of the invention;

FIG. 7 is a cross-sectional view of a ram showing another of the metering structures; and

FIG. 8 is a horizontal longitudinal cross-sectional of a modified hydraulic unit incorporating a resilient cushioning element.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 to 5, the numeral 1 indicates the hydraulic cylinder mounted in the center sill 3. Cylinder 1 is formed with flanges 5 and 7 in order to mount it solidly in the sill by means of lugs 9 extending inwardly from the sill. Instead of or in addition to the lugs 9, the cylinder may be held stationary by horizontal keys passing through slots in the center sill and between flanges 5 and 7.

Slidably mounted in cylinder 1 is ram 11 formed with the head 13. Ram 11 is formed with chamber 15 having an orifice ring 17 set in the outer end of chamber 15. A retaining ring 19 holds the orifice ring 17 in place. A metering pin 21 is slidably mounted in the chamber 15 with the surfaces 23 adapted to slide against surface 25. The outer surface of the metering pin 21 is formed with a shoulder 27. The wall portion of the metering pin on the end thereof beyond the surface 23 (i.e. on the left in FIG. 1) is thinner than that of the wall portion 29 on the other side of bearing surface 23, also shown on the right in FIG. 1. The ram stem 31 is bored at 33 in order to provide a recess for the coil spring 35 which abuts at its inner end against the shim 37 and at its outer end against the inner end of the metering pin. Coil spring 35 serves to hold the metering pin in closed position until it is subjected to sufiicient fluid pressure to bias it to open position. A diagonal passageway 38 connects chamber 15 to the cylinder chamber on the left side of the ram head. A drive pin 39 is inserted in the ring 17 across the diameter thereof in order to act as a stop for the metering pin.

The end 41 of cylinder 1 is closed by an annular closure member 43 held in place by retaining ring 45 threaded to the inside end of the cylinder. Sealing rings 47 are provided between the inner wall of the cylinder 1 and the outer wall of closure element 43 to prevent leakage between the two walls. A bronze or other suitable bearing 49 is mounted between the closure element 43 and the ram stem in order to provide a suitable surface for the ram to slide back and forth. One end of a rubber or other flexible and/or an expansible boot 51 is fastened to closure element 43 by bead ring 53. The other end of the boot is fastened to the ram stem by means of hand ring 55.

A longitudinal bore 56 extends from the face of the ram head 13 to the outlet 57. The outer end of the bore 56 at the ram head is closed by a threaded pipe plug 59. A cross bore 61 connects the area 63 of chamber 15, adjacent the surface 23, with the bore 56. A threaded pipe plug closes the outer end of bore ,61. An oil deflector ring 67 is mounted on the ram stern opposite outlet 57 by means of drive pins 69 in order to prevent hydraulic fluid from impinging against the boot wall. The ram head is equipped with a piston ring 70 in line with a radially extending bore 71 to seal the area between the ram head and piston wall. Tapered plug 72 closes end of bore 71 and seals it by virtue of the pressure of fluid between the plug 72 and the piston ring.

Also bored in ram head '13 and intersecting bore 71 at right angles thereto is bore 73, which is connected to bore 56 through bore 71. Bore 73 communicates with the cylinder chamber on both sides of the ram head. Loosely mounted in bore 73 is valve stem 75 having at each end a valve closure element 77 and 78 adapted to seat in valve seats 79 and 80, respectively. The valve seats are frusto-conical in content and the valve elements have a rounded or areua'te surface adjacent the valve seats. The rounded or arc'uat'e surface of the valve closure elements enables the valve to close tightly even when the stem 75 is somewhat deflected.

At the opposite side of the ram head there is a second valve structure indicated generally by the numeral 81. This valve comprises an orifice 83 closed by an orifice pin 85 mounted on stem 87 and held in closed position against the orifice ring 89 by means of coil spring 91. Passageways 93 are provided through the ram head in order to permit hydraulic fluid to flow from one side to the other side of the cylinder when valve structure 81 opens. The purpose of valve 81 is to prevent damage to the unit in the event of an impact creating pressure above the design pressure of the unit. Valve 31 is set to open only when the pressure applied to the ram exceeds a predetermined amount and will open to an extent commensurate with the pressure of the fluid.

A threaded screw plug 99 closes opening 101 in the wall of cylinder 1 through which the cylinder is filled with hydraulic fluid. Base plate 103 is threadedly mounted at its center on the end 105 of the ram stem. A passageway 107 connects the area between sealing rings 47 with the boot chamber.

Referring now more particularly to FIGS. 2, 2A, 3, 3A, 4 and 6, a spring plate 110 having a rectangular contour and a circular center opening fits over the cylinder 1 and is adapted to abut against flange 7. A sliding box 112 of rectangular contour is adapted to fit in and slide in the sill 3. Box 112 is formed at the inner end thereof with slots 114 adjacent the top and bottom thereof through which keys 115 extend and serve to attach base plate 103 to the box.

Box 112 is keyed to a coupler 117 by means of key 118 passing through a slot 119 in the center of the box and extending through a slot 120 in the coupler. Reinforcing plates 121 are welded to the inner wall of box 112 at the end of slot 119.

A follower plate 123 corresponding in cross-section to the interior cross-section of the box is welded to the interior wall thereof on the side of key 118 opposite from which the coupling extends out of the box. Plate 123 is adapted to abut against base plate 103 attached to the end of the ram. A spring plate 125 similar to spring plate 110 abuts against blocks 127. Blocks 127 are welded to the inside of the sliding box 112 abutting against movable spring plate 125 at the corners thereof in order to provide fastening means for the bolts about to be described and to form an abutting surface for the keys 115 on draft or pull.

Mounted between the spring plates 110 and 125 at the corners thereof, are four pairs or sets of bolts and spring retaining canisters and bolt guides. Two bolts 129 are diagonally oppositely positioned within the sill 3 and are fastened at one end to blocks 127 by being threaded into tapped holes 131 in the blocks. Collars 132 are fastened to plate 125, concentric with bolts 129 to act as spring guides. The opposite end of bolts 129 have englarged heads 133 welded or otherwise fastened thereto and extend into spring retaining canisters and bolt guides 135. The end of the canisters into which the bolts 129 extend have stop elements 137 welded or otherwise fastened thereto in order to prevent the bolt head from being withdrawn from the canister and to act as an abutting surface for the head 133. The other end of canisters is threadedly fastened at 138 to spring plate 110. The canisters and bolts are of suflicient length to permit maximum travel for which the unit is designed.

In the other-two diagonally opposite corners are bolts 141. One end 143, of bolts 141, is threadedly fastened to the cylinder 1 by being screwed into tapped holes in the flange 7 and cylinder wall. Collars 144 are fastened to spring plate 110 concentric with the bolts to act as spring guides. The other end of bolts 141 extends into spring retaining canisters and bolt guides 145. The opposite ends 147 of canisters are threadedly fastened to spring plate 125 by screwing the threaded ends of the canisters into tapped holes in the corners of the plate. Bolts 141 have enlarged heads 149 welded or otherwise fastened to the end of the bolts and the canisters 145 have stop elements 151 welded to the ends thereof in order to prevent the ends of the bolts 141 from being withdrawn from the canister and to act as an abutting surface for the heads 149. Coil springs 153 surrounding the canisters and bolts are retained between plates 110 and 125. Coil springs 153 serve to return the unit to its starting position after pressure on the unit is relieved.

Referring now to FIG. 5, there is shown a modified type of ram and metering device. Orifice ring 17 has a knife edge 155 defining the orifice opening. The head 157 of metering pin 21 closes the orifice opening. The orifice pin has an elongated stern 159 which extends into the recess 33 of ram stem 31'. A spring collar 161 is held in place in recess 33' by means of two drive pins 163 which fit into annular grooves in the outer wall of the collar 161 and through the wall of ram stem 31. A coil spring 165 is mounted under compression between the shoulder 167 at the end of stem 159 and the collar 161. Another coil spring 169 under compression is mounted between the collar 161 and the shoulder 171 formed at the juncture of the stem 159 and metering pin head 157. The chamber 15 is connected to the cylinder chamber by means of passageways 38. The area of the face of head 157 is greater than that of the surface of the end 172 of the pin, thereby enabling the hydraulic pressure to overcome the spring tension and open the orifice in either direction.

A device shown in FIGS. 1 to 4 operates in the following manner:

The unit is mounted in the sill at the end of a car and the sliding box is keyed to the car coupler. Upon impact of the plate 123 against base plate 103 attached to the end of the ram, the ram moves to the right in cylinder 1 building up pressure in the fluid on the right side of the ram. By reason of the fact that the cross-sectional area of the surface 173 of portion 21 of the metering pin is greater than that of the surface 175 more pressure is exerted on surface 173 than on 175 and the pin will overcome the bias of coil spring 35 and more toward the left, opening the orifice in the orifice ring 17, thereby allowing fluid to pass into chamber 15 and thence through passageway 38 into the low pressure or left side of the cylinder 1. At the instant pressure is built up on the right side of the ram the pin 75 moves to the left causing the valve closure element 77 to close, thereby preventing fluid from the high pressure side of the cylinder from flowing through the passage 56 into the boot while allowing the fluid from the low pressure side of the cylinder to pass through the valve closure element 78 through passage 56 into the boot. As the ram travels to the right in the cylinder, the force of impact is gradually diminished until the coil spring 35 is able to overcome the pressure of the hydraulic fluid and close the orifice. In the event of excessive impact the relief valve 81 opens and permits fluid to flow from the high pressure to the low pressure side of the cylinder. Valve 81 is set to open at design pressure, as for example impact forces above 500,000 pounds. In the event of leakage of fluid from recess 33 past surface the fluid will pass through passageway 61 into passageway 56 and thereby prevent build-up of back pressure in area 63 against the metering pin. Although passageway 61 is pro vided, the unit will function without it since pressure in area 63 will be relieved by chamber 15.

During impacts in buff, spring retaining canisters 145 and bolts 129 move to the right together with the sliding box 112. The spring canisters 135 and bolts 141 remain stationary during impact or buff. After the force of the impact is dissipated the coil springs 153 return the unit to its starting position shown in FIG. 2, 2A, 3 and 3A.

When the unit is subjected to pull or draft, sliding box 112 moves to the left, pulling with it the ram by virtue of the fact that the plate 103, attached to the end of the ram, abuts against the keys 115 which in turn abut against blocks 127 welded or otherwise secured to the end of the box 112. Valve pin moves to the right closing closure element 78. When the ram begins moving to the left, high pressure is created in the cylinder chamber to the left of the ram, forcing fluid through passageway 38 into chamber 15 against shoulder 27 causing the metering pin to open and allowing fluid to flow through the orifice from chamber 15 into the low pressure side of the cylinder to the right of the ram. As the ram moves to the left bolts 129 also move to the left pulling canisters 135 along with them. The spring plate which is screwed fast to the other end of the canisters is similarly pulled to the left causing compression of springs 153. Since bolts 141 are fastened to cylinder 1, canisters 145 remain stationary together with spring plate 125 which separates from box 112. When the force of the draft or pull is dissipated, the coil springs 153 surround ing canisters 145 and their associated bolts, having been compressed, return the unit to its starting position. The cylinder 1 remains stationary and as previously pointed out is held fast to the sill by means of the lugs 9.

The hydraulic unit and metering device shown in FIG. 5 functions in the following manner:

Under buff the ram 11' moves to the right causing metering pin 21 to open the orifice formed by the orifice ring 17'. Hydraulic fluid flows through the orifice into chamber 15' and thence through passageway 38' into the low pressure side of cylinder 1'. As the force is dissipated the coil spring 169 returns the metering pin to closed position. When draft or pull is exerted on the device, the ram 11' moves toward the left causing high pressure fluid in the left-hand side of the cylinder to flow through passageway 38 into chamber 15' causing metering pin 21 to open toward the right by virtue of the fact that the area of the shoulder 171 is greater than that of shoulder 167. The metering pin is guided by means of the snug fitting end 172 and the spring collar 161.

Although springs for retaining the metering pin in closed position and for returning the ram to normal position have been disclosed as being springs under compression, it is apparent that the springs can be under tension if attached at their ends to the bearing surfaces.

Referring to FIG. 7, there is shown a ram and metering structure which is similar to that shown and described in FIG. 1, differing therefrom essentially in the construction of the metering pin. The numeral indicates a ram formed with a stem 181, a central passageway 182 and passageways 184 connecting the chamber 186 to the left-hand side of the cylinder (not shown). The passageway 182 is counterbored at 188 to accommodate pin 190, and interior wall 192 is machined to provide a close fit sliding surface for the metering pin. An orifice ring 196 is mounted in the ram head 198 and is held securely in place against shoulder 200 by means of retaining ring 202 which fits in an annular recess in the ram head. The

seat 204 of the orifice ring 196 is frusto-conical in shape. As is apparent from the drawing, the outer wall of the metering pin at the end 206 is flanged outwardly and has a rounded or arcuate contour to provide a tight fit between the pin and the seat 204 of the orifice ring thereby to prevent free flow of hydraulic fluid between the pin and ring when the pin is in closed position. The arcuate surface of pin end 206 is preferably an arc of a circle having a diameter approximately equal to the vertical distance between the inner and outer ends of frustoconical orifice seat 204. The ram and pin structure is in other respects the same as that shown in FIG. 1, the only essential difference being in the shape of the end or head of the metering pin and the omission of stop pin 39. Since the metering pin seats against orifice seat 204, the stop pin 39 shown in FIG. 1 is unnecessary. The diameter of pin 190 is greater at shoulder 207 than the diameter of the pin end 206 at the point of contact 208 with seat 204, in order to present a larger surface area against which fluid pressure in chamber 186 is exerted to open the orifice.

Referring now to FIG. 8, there is shown a hydraulic unit mounted adjacent the end of a railroad car center sill 3. Mounted within the center sill is a cylinder 209 with its accompanying ram and expansible chamber. The end of cylinder 209 is formed with flange 210 preferably having two equally spaced passageways 211 to accommodate two tie bolts 212. The outer portion of the passageways 211 are counterbored at 214 to accommodate bolt heads 216 which may be formed integrally with bolts 212 or otherwise fastened thereto, thereby to prevent the tie bolts 212 from being pulled out of the flange while at the same time permitting the flange and cylinder to move axially while the tie bolts remain stationary. The opposite ends 218 of tie bolts 212 are threaded into openings in ring member 220. The tie bolts 212 pass through passageways in a cylindrically-shaped resiliently compressible cushioning element or body 222, preferably made of a plurality of alternating annular rubber pads and metal plates similar to that shown and described in US. Pat. No. 3,265,222 to Goldman. Element 222 is normally held under partial compression between ring member 220 and flange 210. The ring member 220 is loosely mounted on the outer wall of cylinder 209 in order to allow relative axial movement between the ring and cylinder.

Suitable lugs 224 are rigidly fastened to the center sill 3. Cylinder head end 226 abuts against the lugs 224 when the hydraulic unit is in neutral position or under bufl.

Suitable lugs 228 are rigidly fastened to the center sill spaced from lugs 224 a distance to snugly accommodate therebetween the solid cushioning cylinder 222, ring 220 and flange 210. While ring 220 and tie bolts 212 remain stationary cylinder 209 can move axially a distance equal to that of the maximum draft stroke of the unit.

The outer wall of opposite end 230 of cylinder 209 is threaded at 232 to accommodate threaded spring plate or collar 234. Ram 236 is anchored to element 238 which serves as a coupling member, and as a guide for the ram, and other functions to be described. The end 240 of the ram stem 181 is threaded to element 238 and prevented from turning therein by drive pin 242. The walls 244 of element 238 provide a loose sliding surface against the inner side walls of the sill structure and function to guide the ram in a straight line direction. Element 238 is hollow and generally rectangular in contour. The top and bottom walls are provided with openings 246 through which a pin can be inserted vertically to coupling element 238 to a conventional car coupler 248.

Element 238 is formed with a spring-retaining Wall 250 to retain one end 251 of the coil spring 252. The other end 253 of the coil spring seats against the spring plate or collar 234. The coil spring 252 serves to return the hydraulic unit to its neutral or starting position shown in FIG. 8.

As will be seen from FIG. 8, the center sill flares outwardly at 254 to accommodate the element 238. At the juncture of the main sill 3 and the widened portion 254 are located stop blocks 256 which function to limit the buff stroke of the unit. Blocks 256 are positioned so that wall 258 of element 238 abuts against the blocks 256 just prior to the time the ram head reaches the cylinder and/ or head 226. For example, if the unit is designed for 15-inch buff travel, the distance between the end 260 of blocks 256 and wall 258 will be 15 inches when the unit is in neutral position (shown in FIG. 8) and the distance between the face of the ram head and the inner surface of the cylinder head 226 will be 15% inches, thus preventing the ram head from impacting against the cylinder head.

Mounted on the widened portion 254 of the center sill in front of the end 262 of the element 238 are stop lugs 264 to limit the stroke of the hydraulic unit on draft. The unit is designed so that the end 262 will strike the stop lugs 264 before cushioning element 222 goes solid. For example, the cushioning element may have a travel of 1% inches before it goes solid, and the distance between the lugs 264 and end 262 of unit 238 wi l be 1 inch. By providing a resilient cushioning element having a travel slightly greater than the maximum draft stroke of the ram from its neutral position, danger of damage to the entire unit by reason of excessive force of the ram head against the closure member 43 at the forward or rod end of the cylinder is avoided since the cushioning element permits the cylinder to move with the ram and gradually diminish the force exerted by the ram against the element 43 and also diminish the force with which the end 262 strikes the lugs 264. By providing lugs 264 to limit the draft stroke and the rubber cushioning elements, the danger of the ram being pulled out of the cylinder in the event of a sudden draft impact is avoided.

The width of the hollow interior of element 238 increases, from the end to which the ram stem is attached, to the end 262 in order to provide sufficient space for a car coupler to swing horizontally over an angle of at least 14 in either direction when the hydraulic unit is in neutral position.

The ram and metering structures used in the unit shown and described in FIG. 8 may be any of those previously described, but I prefer the structure shown and described in FIG. 7.

Whereas the cushioning units shown in FIGS. 1 to 3 are designed so that the ram head is spaced a short distance from the cylinder when in neutral position, in FIG. 8 the ram head abuts the end of the cylinder when in neutral position and therefore if the unit is subjected to draft when the unit is in neutral position, the solid cushioning unit surrounding the cylinder functions alone to cushion the impact. However, during in-train service when cars are alternately being subjected to impact and draft, as for example when a train goes down and then up hill, the hydraulic unit functions until the hydraulic unit is fully extended to neutral position and the solid cushioning unit continues to act until the coupling unit strikes the stop lugs to limit the draft stroke.

While the invention has been described as being particularly useful as a hydraulic unit for attachment to the end of railroad cars, it may be used in any environment where it is desired to provide cushioning effect against both impact and pull forces.

I claim:

1. A hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushioning member comprising a resiliently compressible member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said member being attached to said cylinder by tie bolts passing through said member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts.

2. A railway car having a center sill with a hydraulic unit mounted adjacent the end of said sill between lugs on said sill, said hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cyclinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushioning member comprising a resiliently compressible body member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said lugs being spaced apart a distance just sufi icient to accommodate said solid compressible cushioning member, flange and ring.

3. A hydraulic cushioning unit comprising a cylinder, 8. ram slideable mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram charterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushioning member comprising a resiliently compressible body member surrounding said cylinder and mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said cylinder being divided into two closed chambers by said ram and said meter device allowing flow of hydraulic fluid between said two chambers and said metering device being so constructed that it will open and allow passage in either direction between said chambers, the direction of flow depending on the relative pressures in the two chambers, and an expansible chamber connected to said two cylinder chambers.

4. A hydraulic unit in accordance with claim 3 including a double acting check valve in said ram controlling a first passageway through said ram connecting said two chambers, said valve being adapted to cut off communication between one of said cylinder chambers and said expansible chamber and provide communication between said other cylinder chamber and said expansible chamber when the ram is subjected to draft; and to cut oif communication between said other cylinder chamber and said expansible chamber and provide communication between said one cylinder chamber and said expansible chamber when the ram is subjected to buff.

5. A railway car having a center sill with a hydraulic unit mounted adjacent the end of said sill between lugs on said sill, said hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushion ing member comprising a resiliently compressible body member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said cylinder being divided into two closed chambers by said ram and said meter device allowing flow of hydraulic fluid between said two chambers and said metering device being so constructed that it will open and allow passage in either direction between said chambers, the direction of flow depending on the relative pressures in the two chambers, and an expansible chamber connected to said two cylinder chambers, said lugs being spaced apart a distance just suflicient to accommodate said cushioning member.

6. A railway car having a center sill with a hydraulic unit mounted adjacent the end of said sill between lugs on said sill, said hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushioning member comprising a resiliently compressible body member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said cylinder being divided into two closed chambers by said ram and said meter device allowing flow of hydraulic fluid between said tWo chambers and said metering device being so constructed that it will open and allow passage in either direction between said chambers, the direction of flow depending on the relative pressures in the two chambers, and an expansible chamber connected to said two cylinder chambers, a double acting check valve in said ram controlling a first passageway through said ram connecting said two chambers, said valve being adapted to cut off communication between one of said cylinder chambers and said expansible chamber and provide communication between said other cylinder chamber and said expansible chamber when the ram is subjected to draft; and to cut off communication between said other cylinder chamber and said expansible chamber and provide communication between said one cylinder chamber and said expansible chamber when the ram is subjected to bulf, said lugs being spaced apart a distance just sufficient to accommodate said cushioning member.

7. A railway car having a center sill with a hydraulic unit mounted adjacent the end of said sill between lugs on said sill, said hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushion member comprising a resiliently compressible body member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said cylinder being divided into two closed chambers by said ram and said meter device allowing flow of hydraulic fluid between said two chambers and said metering device being so constructed that it will open and allow passage in either direction between said chambers, the direction of flow depending on the relative pressures in the two chambers, and an expansible chamber connected to said two cylinder chambers, said lugs being spaced apart a distance just suflicient to accommodate said cushioning member and in which said ram stem is fastened to a coupling member adapted to slide in said sill, and said sill having spaced lugs to coast with said coupling member to determine the end of the stroke of the ram on both butt and draft.

8. A railway car having a center sill with a hydraulic unit mounted adjacent the end of said sill between lugs on said sill, said hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in the cylinder, said ram having a stem the end of which extends outside said cylinder, and a metering device for metering flow of hydraulic fluid from the high pressure to the low pressure side of said ram characterized in that a cushioning member is attached to said cylinder in such manner that the force required to move said cylinder axially in a direction toward said stem end is increased by resisting the movement of said member in the same direction, said cushioning member comprising a resiliently compressible body member surrounding said cylinder and mounted between a flange on said cylinder and a ring slideably mounted on said cylinder, said body member being attached to said cylinder by tie bolts passing through said body member with one end of said bolts engaging said ring and the other end engaging said flange in such manner as to allow the flange to move toward said ring without movement of said bolts, said cylinder being divided into two closed chambers by said ram and said meter device allowing flow of hydraulic fluid between said two chambers and said metering device being so constructed that it will open and allow passage in either direction between said chambers, the direction of flow depending on the relative pressures in the two chambers, and an expansible chamber connected to said two cylinder chambers, a double acting check valve in said ram controlling a first passageway through said ram connecting said two chambers, said valve being adapted to cut off communication between one of said cylinder chambers and said expansible chamber and provide communication between said other cylinder chamber and said expansible chamber when the ram is subjected to draft; and to cut off communication between said other cylinder chamber and said expansible chamber and provide communication between said one cylinder chamber and said expansible chamber when the ram is subjected to bufl, said lugs being spaced apart a distance just sufiicient to accommodate said cushioning member and in which said ram stem is fastened to a coupling member adapted to slide in said sill, and said sill has spaced lugs to coast with said coupling member to determine the end of the stroke of the ram on both buff and draft.

9. A hydraulic cushioning unit comprising a cylinder, a ram slideably mounted in said cylinder, a passageway formed in said ram extending between the low and high pressure sides thereof and including an orifice, and a metering pin shiftably mounted in said ram and cooperating with said orifice to control flow of hydraulic fluid from the high pressure to the low pressure side of said ram through said passageway, characterized in that the surface of said orifice is frusto-conical and a surface of said pin is adapted to abut said orifice surface when the pin is in closed position thereagainst, said pin surface having an arcuate contour, the diameter of said pin surface at the point of contact with said orifice surface being intermediate the greatest and smallest diameters of said orifice.

10. A hydraulic cushioning unit in accordance with claim 9 in which the pin surface of arcuate contour is a segment of a circle having a diameter of approximately the same length as the vertical distance between the ends of the orifice.

11. A hydraulic cushioning unit in accordance with claim 10 in which said pin is slideably mounted in a chamber and is formed with a shoulder within said chamber and spaced from said arcuate portion of said pin, the diameter of the pin at the shoulder being greater than the diameter of the pin at the point of contact of the arcuate surface with the orifice surface.

12. In a railroad car having a center sill structure fixed thereto, a cushioning arrangement therefor comprising:

a hydraulic cushioning unit positioned adjacent and within one end of said sill structure,

said cushioning unit comprising:

a cylinder having a head end and a rod end,

a ram including a piston head slideably mounted in said cylinder for movement between said ends thereof, said ram extending longitudinally of said sill structure and outwardly of said cylinder rod end,

said cylinder rod end facing outwardly of the car,

and means for metering hydraulic liquid flow within said cylinder on buff and draft impacts being applied to said cushioning unit to cushion the application of such impacts to said sill structure,

a guide member mounted in said center sill structure outwardly of said cushioning unit for movement longitudinally of said sill structure,

megtns for guiding said movement of said guide memer, said ram being fixed to said guide member, means for operatively connecting a car coupler to said guide member, means for biasing said ram head toward said rod end of said cylinder, and means for securing said cylinder to said sill structure against buff and draft impacts applied to said cushioning unit including resilient cushion means interposed between said cylinder and said sill structure for absorbing draft impacts when said ram piston head is adjacent said rod end of said cylinder. 13. The cushioning arrangement set forth in claim 12 including:

stop means carried by said sill structure and engageable by said guide member for limiting movement of said guide member and ram in buff and draft.

References Cited UNITED STATES PATENTS 2,342,578 2/1944 Giannini 188-96.5 3,011,778 12/1961 Yntema 267-64 3,150,782 9/1964 Campbell et al. 213-43 3,150,783 9/1964 Campbell et al. 213-43 3,164,264 1/1965 Price et al 21343 3,275,164 9/1966 Peterson 21343 DRAYTON E. HOFFMAN, Primary Examiner US. Cl. X.R. 

